The Department for Communities and Local Government (now DLUHC) issued revised and updated guidance in September 2013  for councillors on the Code of Conduct. It is called Openness and transparency on personal interests, a guide for councillors. 

The guidance can be found here

However, since that guidance was issued a new Code of Conduct has been agreed. The Local Government Association (LGA) issued a revised Code in June 2020 and associated guidance 

In Oxfordshire the Monitoring Officers agreed on an adapted version of the LGA Code and adopted it across all tiers of local government - county, district and parish.

Your own district council has the Code on its website, with more information, guidance and advice about how to make a Code of Conduct complaint. For example the South Oxfordshire District Council website 

The Code has at its heart the Nolan Principles of Conduct in public life:

• selflessness

• integrity

• objectivity

• accountability

• openness

• honesty

• leadership